Bartonella Infection

Serology and culture are very useful to confirm a diagnosis of cat scratch disease (CSD), trench fever, Carrión disease, and endocarditis caused by Bartonella species. However, serology generally requires the comparison of paired acute and convalescent sera to confirm diagnosis. For accurate comparison of paired sera, samples should be tested in a single laboratory at the same time. Culture for Bartonella species should be incubated for at least 21 days. Because of the long turnaround time required for these techniques, treatment decisions should be informed by clinical evaluation and patient history and should not be delayed for definitive laboratory diagnosis. Polymerase chain reaction (PCR) testing may be useful to diagnose CSD, Carrión disease, and endocarditis. Carrión disease may also be diagnosed using a peripheral blood smear. PCR and blood smears are more rapid than culture or serology and may inform treatment decisions. 

Cat scratch disease (CSD) is transmitted through the scratch of domestic or feral cats carrying fleas infected with Bartonella henselae. CSD diagnostic testing may be appropriate for patients exhibiting CSD symptoms with previous exposure to cats and recent scratch history. Trench fever is transmitted by the human body louse. Testing for trench fever may be appropriate in patients with characteristic symptoms who are at increased risk for human body lice (eg, persons experiencing homelessness or living in areas with poor sanitation). Carrión disease is transmitted through female sand flies, primarily in high-elevation areas of the Andes Mountains, and should be considered in patients who have traveled to that region or have been in contact with someone who has traveled to that region. 

Cat scratch disease (CSD) is often characterized by low-grade fever, enlarged and/or tender lymph nodes (1-3 weeks postexposure), and a papule or pustule at the scratch site. In some cases, eye infections, severe muscle pain, or encephalitis may occur. Trench fever generally presents with fever (one time or relapsing), headache, rash, and bone pain. Carrión disease occurs in two distinct phases. The first, Oroya fever, may include symptoms such as fever, headache, muscle aches, and abdominal pain. The second phase, verruga peruana (Peruvian warts), is characterized by the formation of growths under the skin that develop into red to purple vascular sores. Bacillary angiomatosis (BA) occurs most frequently in people with weakened immune systems (eg, patients with advanced HIV infection) and may result in lesions in or under the skin, in bone, or in other organs.

Because Bartonella symptoms are often generalized, the testing strategy should also be informed by patient history.